Ally I'm on the way out the door to work so don't really have time to check to out but a quick google search shows that it's for activating Time Warner modems.

The 3rd search result in this google search says something about it not being legit but I didn't take the time to read all of the replies.

Here's the google search results-
https://www.google.com/search?q=elb02.activatemymodem.comngs.html+&ie=utf-8&oe=utf-8&client=firefox-b-1

You may want to do a search with both Spectrum modem and elb02.activatemymodem.comngs.html in it to see if it does have something to do with your modem.